3 Bureau of Prisons employees hospitalized over drug-laced prisoner mail

Lawmakers are questioning the agency's procedures for safe handing of prisoners' mail.

Three Bureau of Prisons employees at United States Penitentiary Thompson in Illinois have had to go to the hospital over the past two weeks, according to the local union president, prompting two members of Congress to write a letter to the agency questioning how mail for prisoners is processed.

"We write with concern about reports of unsafe conditions for correctional officers in opening mail for incarcerated persons," the letter written by Rep. Cherri Bustos, D-Ill., and Senate Judiciary Committee Chairman Dick Durbin, D-Ili., and obtained by ABC News, said.

"We know that it is critical for incarcerated persons to have access to correspondence while serving their sentences. Unfortunately, mail is also one of the ways in which drug contraband can be brought into correctional facilities," the lawmakers wrote.

One staff member was hospitalized on Friday. The drug involved and the officer's condition are unknown.